Kitchen Countertop Backsplash Problem (photo added)

Recently had some countertop installed by an unnamed Big Box store. The counter itself went fine. However, the backsplash is another story.

I guess my walls are not truly plumb because the backsplash doesnt really sit flush. In fact, in some places, there is as much as a 1/8 inch gap. Unsightly more than anything, but I also worry about water getting back there. (I finally got a photo added)

What is the best solution (the installer is not responsible for correction of backsplash due to non-plumb walls, per contract - I looked)? I could caulk but the gaps are pretty wide in places. Afraid it might just run down. But if I did, would folks suggest a clear caulk? Or something to match/compliment counter color?

Or could/should I maybe spray some Gap Filler like Great Stuff down in there first and let it dry. Then caulk? Gives caulk something to sit up on. Is there a chance that stuff could expand and damage backsplash?

I could caulk but the gaps are pretty wide in places. Afraid it might just run down. But if I did, would folks suggest a clear caulk? Or something to match/compliment counter color?

Mike is right. Without a pic, all you're going to get are guesses.

One possibility: Google "backer rod". It's a stiff foam type rod that can be stuffed into larger gaps before caulking. Most likely found in with the weatherproofing stuff at that Big Box store. I would use it before using anything expanding. Then cover with caulk.

There is not much you can do with that. You could stuff some foam backer-rod in the crack then caulk it but it will still be a "what-you-see-is-what-you-get" kind of a problem.

I gotta tell ya tarheel that is a path-of-least-resistance kind of installation job on the part of the installers. When that happens (and it does happen frequently) the installer usually gouges out some drywall here and there so that the backsplash fits into the wall just a little. That would take some extra effort however.

My suggestion is to (if you don't want to add ceramic tile to the wall overall) buy some ceramic tile bullnose only. Glue the bullnose to the wall. It will cover the unsightly gap and may even pretty things up a little.